The primary objective of the proposed research is to examine the mechanisms of cellular protection from lung injury, particularly injury arising from exposure to endotoxin and increases in oxygen tension. Many of these studies will be performed in vivo, utilizing a number of different animal models, including mutant mouse strains. Some of these strains have been previously derived, but many of the strains for the proposed research program will be developed through a central core that will produce transgenic and knockout lines of mice. This Transgenic Mouse Core is located in the Rangos Research Center of the Children's Hospital of Pittsburgh, partly in the laboratory of the Director of the Core, Dr. J. Richard Chaillet, and partly in space shared by the Transgenic and Chimeric Mouse Facility (TCMF) of the University of Pittsburgh. Dr. Chaillet is also Director of the TCMF. The Transgenic Mouse Core will generate transgenic mouse lines via the injection of DNA constructs into the pronuclei of fertilized eggs. As well, the Core will produce targeted mutations in mouse ES cells via the electroporation of targeting constructs, followed by the injection of mutant ES cells into mouse blastocysts to generate chimeric mice. Chimeric mice generated in this manner are then used to generate established mutant mouse lines with targeted mutations of known endogenous genes. Lastly, the Core will retrieve mouse lines from sources outside the University of Pittsburgh via the shipment of preimplantation embryos and their transfer into pseudopregnant female mice. All of the individual proposed research projects will extensively utilize the Transgenic Mouse Core. The director and staff of the Transgenic Mouse Core and the TCMF all have considerable experience with the transgenic mouse and ES cell techniques that are needed for the proposed research projects.